Motion tracking: I have a solve. Now how to get the camera position for each video frame?
When you solve a camera using tracking, blender creates a Camera Solver Constraint.
To clear such constraint, convert the camera motion to keyframes.
Select the camera and use Constraint to F-Curve in the Object Constraint Properties.

More info:
https://docs.blender.org/manual/en/latest/animation/constraints/motion_tracking/camera_solver.html